The present disclosure herein relates to a semiconductor device, and more particularly, to a differential driving circuit used for communication between semiconductor devices.
As the IT technology combined with automobile technology is diversified, functions and kinds of semiconductor devices mounted on a vehicle are also being diversified. Accordingly, communication techniques between semiconductor devices in an automobile system have become important.
In the communication between semiconductor devices, a differential driving circuit, which is immune to noises and is capable of transmitting and receiving data with a high speed, are widely used. The controller area network (CAN) communication method which is one of interfaces used in automobile systems is a kind of communication methods using such a differential driver. The CAN communication method is developed for data transmission between modules in a vehicle, is immune to noises, and has various error compensation functions. Thus, the CAN communication method is most widely used for data transmission and reception which are necessary for vehicle control in a vehicle requiring high safety.
In designing such a CAN bus driving circuit, the symmetry of an output signal of a differential driver is one of important characteristics which should be first considered. When the symmetry characteristic of the output signal of the CAN bus driving circuit is degraded, the common mode voltage of the output signal is changed over time. As a result, the electro-magnetic interference (EMI) characteristic of the CAN bus driving circuit is degraded. Especially, since the CAN communication method is mainly used inside a vehicle, the degradation of the EMI characteristic is an important problem which can affect the safety of vehicles.